Searching \ for 'Humidity Sensors' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/io/sensors.htm?key=sensor
Search entire site for: 'Humidity Sensors'.

Truncated match.
PICList Thread
'Humidity sensors'
1998\08\13@174330 by Jeff Dill

flavicon
face
Hi, all

I have seen mention of the Hycal humidity sensors on this list in
the past, and after looking around, have decided they look to be the
most interesting.

However, I can not find them for sale at any of the electronics
distributors that I have checked with.

Does anyone have any information on where I may purchase a small
quantity of these (IH-3605) parts?

Thanks for the help.

Jeff Dill

1998\08\16@125956 by Tom Handley

picon face
  Jeff, HyCal's humidity sensors are sold by Honeywell/Microswitch. Check
the following link:

     http://www.honeywell.com/sensing/prodinfo/humiditymoisture/

  I've been using their sensors in my PIC-based weather station for around
18 months. The outdoor sensor is an IH-3602L which comes in a T0-39 can with
a slotted cap. For the indoor sensor, I use the IH-3605 hybrid element. Both
sensors operate from 1 - 100% and provide an output from around 0.8V - 3.9V
with a 5V supply. They should be buffered and require a simple low-pass
filter as well as shielding from bright light. You also need to know the
ambient temperature. Normally you combine the humidity and temperature
sensor in a suitable enclosure. In my case, I used an LMC660 quad CMOS
op-amp. The sensor output goes through a voltage follower, then a simple R/C
filter, and another follower to the A/D. In addition to humidity, I use it
to calculate dew point and heat index. It seems to track the local NWS at
Portland OR's airport very closely but that's a hard call as there are two
major rivers that run through the city and several `micro climates'.

  - Tom

At 05:31 PM 8/13/98 -0400, Jeff Dill wrote:
{Quote hidden}

Tom Handley
New Age Communications
Since '75 before "New Age" and no one around here is waiting for UFOs...


'Humidity sensors'
1998\10\15@024041 by Dan Larson
flavicon
face
Does anyone know where I can obtain onesies of the
HyCal humidity sensors?

This sounds like the best one to use for the PIC
and I remember the discussion on it from a while
back.

I have looked at the Philips sensor and it looks
like it is too much trouble for the cost ($13
from Newark) given its non linear output and need
to be incorporated into an oscillator to read it.

Do you think "pinging" it through a resistor from
a PIC pin would be reliable enough to read a capacitance
from 120pf to 180pf ? Even then, it is not linear
so tables would needed.

Over all, the HyCal seems better... but where can
I get one ?!?

Any other opinions on this matter?  I want to build
a hygrometer with a single display / keypad panel
and data collection in EEPROM.  This display unit
would then interface with multiple temp / humidity
sensor pods, one in each location.  Each pod would
use a PIC to read the sesnors and send the data to
the display / data collection unit.  The data
collection unit could dump readings to a PC via
RS-232 interface.

Dan


'Humidity Sensors'
2000\02\09@124423 by Andy Kunz
flavicon
face
I've been quiet lately due to being busy.  Nice change, huh?

I need to know what folks are using to measure humidity.  I need to know
the humidity in a human-occupied room (it wasn't specified if it were
relative or absolute - which do I want?) in order to keep it within comfort
limits.

What are you guys (and gals) using?  How does it interface?  If you could
re-do the project, would you use the same thing (assuming code changes are
acceptable).

I'm hoping for a single analog or PWM input.

Thanks.

Andy

==================================================================
New Microprocessor support forum mail list - details on our site
------------------------------------------------------------------
spam_OUTandyTakeThisOuTspamrc-hydros.com      http://www.rc-hydros.com     - Race Boats
.....andyKILLspamspam@spam@montanadesign.com  http://www.montanadesign.com - Electronics
==================================================================

2000\02\09@131308 by Matt Burch

flavicon
face
The Honeywell/Hycal HIH-3605 is a nice but expensive (>=$30) unit that
provides an analog output proportional to relative humidity. I'm using the
NIST-traceable version (even more $$$) in a project to provide exact
humidity calibration for each unit.

For a great listing of all things sensor-related, see Brooke's Sensor Page:
http://www.pacific.net/~brooke/Sensors.shtml

mcb


At 12:38 PM 02/09/2000 -0500, Andy Kunz wrote:
{Quote hidden}

-------------------------------------------------------------------
    Matt Burch      |  Pinnacle Technology   | tel: (785) 832-8866
 Project Engineer   | 619 E. 8th St. Suite D | fax: (785) 749-9214
EraseMEmburchspam_OUTspamTakeThisOuTpinnaclet.com |  Lawrence, KS  66044   |  http://www.pinnaclet.com
-------------------------------------------------------------------

2000\02\09@131930 by Darren Logan

picon face
Hello,

   I thought you might be interested in this site:

   http://www.michell.co.uk

   world leaders in moisture / humidity measurement.

Vbr,
   Darren Logan BSc

2000\02\09@151433 by Barry King

flavicon
face
Andy asked:
> I need to know what folks are using to measure humidity.  I need to know
> the humidity in a human-occupied room (it wasn't specified if it were
> relative or absolute - which do I want?) in order to keep it within comfort
> limits.

So you probably want relative humidity (%RH).  That's what is usually
used for HVAC applications.  If you are considering temperature and
humidity for "comfort", you can measure either way, but I think
you'll find the reference material for target comfort ranges are
typically in terms of %RH.

> What are you guys (and gals) using?

Two possibilities I've used:

General Eastern makes complete calibrated sensors.  Their RH-5 series
is 0 to 5 V out = 0 to 100% RH.  They are widely used in HVAC, and
are packaged for room air, duct, or outdoor already.  So, easy to
use, but maybe more money?  They aren't on the web AFAIK, so try: 1-
800-225-3208 (Woburn, MA)

Panametrics makes Humidity instruments based on capacitive sensors.
They will sell you the cheap uncalibrated bare sensor element, they
call it a MiniCap 2.  I built a CMOS 555 based humidity sensor, then
converted to uC driven charge/dicharge timing arangement.  It worked,
but we never really solved the calibration problem before the project
was obsoleted.  Also no www site, Waltham MA, 800-833-9438.

P.S. I have no idea why Massachusetts is the capital of humidity
measurement, and lets not start any threads speculating about what
the political or other regional stereotype reasons might be :)

Barry.
------------
Barry King, Engineering Manager
NRG Systems "Measuring the Wind's Energy"
http://www.nrgsystems.com
Phone: 802-482-2255
FAX:   802-482-2272

2000\02\09@152917 by Alice Campbell

flavicon
face
try
http://www.figarosensor.com/gaslist.html

for cheap ones like microwave ovens use to turn off the popcorn
before it bursts into flame..


>
> I need to know what folks are using to measure humidity.  I need to know
> the humidity in a human-occupied room (it wasn't specified if it were
> relative or absolute - which do I want?) in order to keep it within comfort
> limits.
>
> What are you guys (and gals) using?  How does it interface?  If you could

alice
token gal
(i prefer intelligent enabled entity, myself)

> re-do the project, would you use the same thing (assuming code changes are
> acceptable).
>
> I'm hoping for a single analog or PWM input.

2000\02\09@174650 by Larry G. Nelson Sr.

flavicon
face
My guess would be for relative humidity. I used to use sensors from
Panametrics and I think it was called a Microcap II ?? It worked OK and was
fairly cheap by comparison. It did have a low maximum voltage and the ap
note used a 555 circuit that can be done better with a PIC.


At 12:38 PM 2/9/00 -0500, you wrote:
{Quote hidden}

Larry G. Nelson Sr.
KILLspamL.NelsonKILLspamspamieee.org
http://www.ultranet.com/~nr

2000\02\09@203749 by Robert A. LaBudde

flavicon
face
<x-flowed>At 12:38 PM 2/9/00 -0500, Andy wrote:
>I need to know what folks are using to measure humidity.  I need to know
>the humidity in a human-occupied room (it wasn't specified if it were
>relative or absolute - which do I want?) in order to keep it within comfort
>limits.
>
>What are you guys (and gals) using?  How does it interface?  If you could
>re-do the project, would you use the same thing (assuming code changes are
>acceptable).

1. For pre-calibrated, +/- 3% capacitance-based sensor (measure via astable
or one-shot), go to: http://www.geinet.com/RH/rhgcap.htm

2. For cheap, you-have-to-calibrate-each-one-yourself capacitance-based
sensors,  go to:

http://www.panametrics.com/div_pci/pages/products/rehumidity/minicap2.shtml


================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: RemoveMEralTakeThisOuTspamlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causae scire"
================================================================

</x-flowed>

2000\02\10@123930 by Tom Handley

picon face
  Andy, the following is a `snippet' from my standard humidity sensor
question message:

--------
  Low-cost humidity sensors behave like capacitors that vary with
humidity to change the frequency of an external oscillator. Typical relative
humidity ranges from 10 - 90%. Philips makes (or use to) a low-cost sensor
(P/N 2322 691 90001). General Eastern also have low-cost sensors in their
G-CAP line. Their sensors cover 1 - 100% RH.

  For my PIC-based weather station, I needed better accuracy and I wanted
to reduce the complexity of the support circuitry. I ended up using HyCal
sensors which provide an output within 0 - 5V and require minimal support.
The outdoor sensor is an IH-3602L which comes in a T0-39 can with a slotted
cap and for the indoor sensor, I used the IH-3605 hybrid element. Both
sensors operate from 1 - 100% and provide an output from around 0.8V - 3.9V
with a 5V supply. They should be buffered and require a simple low-pass
filter and, as with most sensors of this type, need to be shielded from
sources of bright light. You do need to factor in temperature compensation
so you need to measure ambient temperature near the sensor. You normally
combine both in a package for your outdoor sensors.

  There are more sophisticated sensors that provide a voltage, current, or
pulse output and include the temperature sensor giving humidity and/or dew
point. For more info contact:

     HyCal: www.honeywell.com/sensing/prodinfo/humiditymoisture
     General Eastern: http://www.geinet.com/
     Omega          : http://www.omega.com
     Philips        : (817) 325-7871 (Note, may be discontinued...)
--------

  As I mentioned above, I used the Honeywell/HyCal sensors. In your case,
you could use the IH-3605 hybrid element. I supplied +5V to the sensors and
buffered the outputs with an LMC660 quad Op Amp using a +12V supply. While
the LMC660 has a rail-rail output, it's input common mode range is much less
and would not be suitable for a +5V supply in this application due to the
output range of the IH-3605. If you are only using one sensor, then a LMC662
would suffice. The sensor first goes to a voltage-follower followed by a
simple R-C filter and through another follower to the A/D. Though I used a
MAX186, an 8-Bit A/D is fine for this application.

  For "Comfort level", Dewpoint is actually more relevant. You will need to
install a temperature sensor with the humidity sensor. In general, a
Dewpoint above 60 starts to feel `sticky'. The downside for a PIC is the
Dewpoint calculation... There are a lot of methods to find the Dewpoint. In
my weather station, I already had a large SRAM so I used some rather
complicated but very accurate equations to generate a data table. The
following is a simplified method which still provides good results. Also,
you are probably only interested in a small range of values so you might
still want to generate a data table. Note, I broke the equation up into
smaller pieces for convenience.

     Tc  = (Tf - 32) / 1.8
     a   = (7.5 * Tc) / (237.7 + Tc)
     Pw  = 6.11 * 10^a
     Pwp = Pw * (RH / 100)
     b   = log10(Pwp) - log10(6.11)
     DPc = (237.7 * b) / (7.5 - b)
     DPf = (DPc * 1.8) + 32

     Where:
        RH  = Relative Humidity (%)
        Tf  = Temperature (F)
        Tc  = Temperature (C)
        DPc = Dewpoint (C)
        DPf = Dewpoint (F)

  - Tom

At 12:38 PM 2/9/00 -0500, Andy Kunz wrote:
{Quote hidden}

------------------------------------------------------------------------
Tom Handley
New Age Communications
Since '75 before "New Age" and no one around here is waiting for UFOs ;-)

2000\02\10@132755 by Andy Kunz

flavicon
face
At 06:19 AM 2/10/00 -0800, you wrote:
>   Andy, the following is a `snippet' from my standard humidity sensor
>question message:

Thanks.  That's the best write-up I've seen on the subject.

Andy

==================================================================
New Microprocessor support forum mail list - details on our site
------------------------------------------------------------------
spamBeGoneandyspamBeGonespamrc-hydros.com      http://www.rc-hydros.com     - Race Boats
TakeThisOuTandyEraseMEspamspam_OUTmontanadesign.com  http://www.montanadesign.com - Electronics
==================================================================

2000\02\10@161138 by Tom Handley

picon face
  Andy, let me know if I can help. I wrote a simple C program that runs
in DOS to calculate and download Dewpoint (as well as Wind Chill and Heat
Index) data to my weather station via the serial port. I can easily modify
it to give you a data table within a given range.

  - Tom

At 01:11 PM 2/10/00 -0500, Andy Kunz wrote:
>At 06:19 AM 2/10/00 -0800, I wrote:
>>   Andy, the following is a `snippet' from my standard humidity sensor
>>question message:
>
>Thanks.  That's the best write-up I've seen on the subject.
>
>Andy


------------------------------------------------------------------------
Tom Handley
New Age Communications
Since '75 before "New Age" and no one around here is waiting for UFOs ;-)

2000\02\10@185134 by Andy Kunz

flavicon
face
At 12:30 PM 2/10/00 -0800, you wrote:
>   Andy, let me know if I can help. I wrote a simple C program that runs
>in DOS to calculate and download Dewpoint (as well as Wind Chill and Heat
>Index) data to my weather station via the serial port. I can easily modify
>it to give you a data table within a given range.

I don't think that will be needed.  It's going in a room to allow us to
keep the wallpaper from peeling in the summer and drying out the timber in
the winter.  Real wide limits, just to get a basic idea of why the mold is
so thick <G>

Andy
==================================================================
New Microprocessor support forum mail list - details on our site
------------------------------------------------------------------
RemoveMEandyspamTakeThisOuTrc-hydros.com      http://www.rc-hydros.com     - Race Boats
andyEraseMEspam.....montanadesign.com  http://www.montanadesign.com - Electronics
==================================================================

2000\02\12@042058 by Peter Crowcroft

flavicon
face
I use the Scimarec one HS-15P

Data sheet and photo is on my website at

http://kitsrus.com/modules.html

I use it in my Kit 75.

Source code how to drive it is on the software download page

http://kitsrus.com/soft.html

I can sell you at $US5 cash note sent to me. Airmail postage included.

regards,

Peter Crowcroft
                   DIY Electronics (HK) Ltd
               PO Box 88458, Sham Shui Po, Hong Kong
Voice: 852-2720 0255   Fax: 852-2725 0610    Email: EraseMEpeterspamkitsrus.com
                      Web: http://kitsrus.com
----------------------------------------------------------------------

More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...